Outputting a warning signal when approaching a protected area warning of an impending mode change

ABSTRACT

A predetermined area is protected from the disturbing usage of mobile terminals (e. g. cell phones) of a wireless communication system. Mode change information is sent over a system information message of a broadcast channel to change the operating mode (e. g. to deactivate) of the mobile terminal. This mode change information contains information, such as, the duration of the mode change, a reason for the mode change and information on groups of mobile terminals that will be exempted from the mode change. Additionally, the mobile terminal transmits an alarm signal to the user if the user is approaching a predetermined protected area.

This is a continuation of copending International ApplicationPCT/EP99/01643 having an international filing date of Mar. 12, 1999.

The present invention relates to a base station for protecting apredetermined area from disturbing usage of mobile terminals of awireless cellular telecommunication system, to a method for protecting apredetermined area from disturbing usage of mobile terminals of awireless cellular telecommunication system and to a mobile terminal fora wireless cellular telecommunication system.

In many areas the use of mobile terminals of wireless telecommunicationsystems is regarded as a nuisance for other people, like in restaurantsor in the opera, or even dangerous in places like hospitals orairplanes. In the first case particularly audible signals output frommobile terminals are disturbing other people or the spectacle beinggiven. In the second case, the use of mobile terminals, particularly thetransmission of high frequency electromagnetic waves, can disturb otherelectronic devices or the like by interfering with their circuitry whatcan lead to severe incidents. It is therefore very important to providea way to protect predetermined areas from a disturbing usage of mobileterminals within these areas. Particularly, the protection of apredetermined area should not depend on the user's will, e. g. on auser's input of information to the mobile terminal.

EP 0 891 110 A1 discloses a method and a system for preventing a mobileterminal from causing disturbance within a predetermined area, e. g.inside a plane or inside of hospitals. Particularly, the disclosedmethod comprises the steps of transmitting a deactivation signal from abase station to a mobile terminal and deactivating a use of the outputof the mobile terminal in response to the deactivation signal. Thereby,the transmission output is deactivated. The base station can either bean ordinary base station or a base station specifically designed formainly transmitting the deactivation signal. Although EP 0 891 110 A1describes, that the base station could be an ordinary base station, itis not disclosed how the deactivation signals could be implemented andtransmitted in an ordinary telecommunication system.

The object of the present invention is therefore to provide a basestation and a method for protecting a predetermined area from disturbingusage of mobile terminals of a wireless cellular telecommunicationsystem, which protects a predetermined area by transmitting mode changeinformation for changing an operation mode of the mobile terminals in asimple and effective way, whereby the mode change information istransmitted on the basis of a wireless cellular telecommunicationsystem. The object of the present invention is further to provide amobile terminal for a wireless cellular telecommunication system, whichcan be controlled by such mode change information so that thepredetermined area is protected from disturbing use of the mobileterminal.

The above object is achieved by a base station for protecting apredetermined area from disturbing usage of mobile terminals of awireless cellular telecommunication system, with generating means forgenerating mode change information for changing an operation mode of themobile terminals to protect the predetermined area, and transmittingmeans for transmitting said generated mode change information withinsaid predetermined area by means of system information messages of abroadcast control channel of a wireless telecommunication system.

The above object is further achieved by a method for protecting apredetermined area from disturbing usage of mobile terminals of awireless cellular telecommunication system, with the steps of generatingmode change information for changing an operation mode of the mobileterminals to protect the predetermined area, and transmitting saidgenerated mode change information within said predetermined area bymeans of system information messages of a broadcast control channel of awireless telecommunication system.

Thus, the base station and the method for protecting a predeterminedarea from disturbing usage of mobile terminals of a wireless cellulartelecommunication system enable a simple and effective way to change theoperation mode of mobile terminals within the predetermined areaautomatically so that the predetermined area is protected.

The base station of the present invention can thereby be an ordinarybase station of the wireless cellular telecommunication system whichadditionally to its usual elements comprises the generating means andthe transmitting means according to the present invention whereby thetransmitting means also transmits normal signalling or user datainformation of the telecommunication system. Alternatively, the basestation of the present invention is a specialised base station with arestricted functionality compared to an ordinary base station. Dependingon the required application, the specialised base station could compriseessentially the generating means and the transmitting means according tothe present invention without further elements for communicating data inthe telecommunication system. This last possibility would present a verysimple and cost-effective way to protect certain areas according to thepresent invention.

The above object is further achieved by a mobile terminal for a wirelesscellular telecommunication system, with transmitting and receiving meansfor transmitting information to and receiving information from basestations of said telecommunication system and for receiving mode changeinformation transmitted from a base station by means of systeminformation messages of a broadcast control channel of the wirelesstelecommunication system for protecting a predetermined area fromdisturbing usage of the mobile terminal, and control means for detectingreceived mode change information and changing an operation mode of themobile terminal depending on the received mode change information sothat said predetermined area is protected.

The wireless cellular telecommunication system can be any known orfuture system using system information messages in a broadcast controlchannel. System information messages are e. g. used, when a mobileterminal is switched on. The mobile terminal will then read thebroadcast system information messages transmitted from a base station ina broadcast control channel. The system information messages usuallycontain information concerning the respective base station and thenetwork, e. g. the timing, the channel structure, the location includingthe network identification and so on. According to the presentinvention, these system information messages are used for thetransmission of mode change information to protect a predetermined area.The predetermined area is thereby the restricted area, in which theparticular base station transmits the mode change information. E. g.,such a predetermined area could be a hospital or a small area around theboarding gate of an airport or inside a plane.

The advantage of the described invention is that it does not rely onpeoples responsibility to switch off their phones, but that it willperform this automatically. This will provide much higher safety to theareas to be protected.

Furthermore the mode change information is broadcast to each phonewithin the cell site, which makes sure that each mobile terminalsupporting the mode change functionality will be reached and preventedfrom disturbing usage. However, it still can be possible to exemptmobile terminals from groups of people, e. g. security personnel, frommode change, so that these can still utilise the communication toolsprovided by mobile telephony.

A further advantage is that the described invention will only require avery small upgrade to existing systems and therefore additionalinvestment in infrastructure is not necessary. All the described areascan be performed by changes to the software of the infrastructure. Theimpact on mobile terminals is also kept to a minimum in order to avoidany major impact on the cost of those terminals. According to thepresent invention, the system information message from the base stationcomprises, consists of or relates to mode change information forchanging an operation mode of the mobile terminal.

Advantageously, the mode change information replace at least partiallythe system information messages in the broadcast control channel.Alternatively, the mode change information is additional information tothe system information in the broadcast control channel. As anotheralternative, the system information messages of the broadcast controlchannel can comprise indicating information indicating a channel inwhich the mode change information is transmitted said channel beingdifferent from the broadcast control channel. In case that the modechange information replace the system information message, the basestation according to the present invention can be built very simple andcheap, since it only needs to transmit the mode change information on aparticular broadcast control channel. A mobile terminal switched onwithin the predetermined area receives the mode change informationinstead of or in addition to the system information message and changesits operation mode correspondingly. The predetermined area to beprotected is usually within a cell or adjacent to one or more cells ofthe telecommunication system. A mobile terminal in one of theneighbouring cells may receive information, but not necessarily, aboutneighbouring base stations within the system information messages fromthe current base station. The channels, on which these neighbouring basestations can be found, are monitored by the mobile terminal and when thesignal of the current base station becomes weaker and the signal from aneighbouring base station becomes stronger, the mobile terminal willeventually switch to the neighbouring cell. In case that the signal froma neighbouring base station is a mode change information according tothe present invention, the mobile terminal will change its mode when thesignal carrying the mode change information receives a certain strength,which indicates, that the mobile terminal is entering the predeterminedarea to be protected.

Advantageously, the transmitting means of the base station regularlytransmits the mode change information. The generating meansadvantageously generates mode change information for switching off atleast the high frequency portion of a mobile terminal receiving saidmode change information. The high frequency portion of a mobileterminal, which comprises e. g. upconverting and downconverting means,is the most important part of a mobile terminal to be switched off foravoiding interference with the circuitry of other electronic or electricdevices in the predetermined area.

Advantageously, it is possible to define additional information in thechange mode information, which can exclude groups of mobile terminalsfrom changing their mode.

Alternatively, the generating means generates mode change informationfor switching a mobile terminal receiving the mode change informationinto a silent mode, e. g. a ringer off or a vibrating device on mode. Inthe silent mode, audible or acoustic signals output from the mobileterminal are at least reduced to low volume to avoid a disturbance inthe predetermined area. Advantageously, the audible signals arecompletely suppressed and replaced by visual signals, vibrating signalsor other non-audible signals.

Advantageously, the mobile terminal of the present invention maintainsthe changed mode as long as the mode change information is received anddetected. The mobile terminal could thereby regularly check if thechange mode information is still received regularly and changes its modeas soon as the mode change information is not received anymore. Themobile terminal could further comprise a timing means for calculatingthe time period since the last reception and detection of a mode changeinformation and for comparing the time period with a predetermined timethreshold, whereby the mobile terminal is reset to the original mode incase that the time period exceeds the time threshold. Alternatively, thecontrol means maintains the changed mode until a time period received astime information with the mode change information has expired, wherebythe mobile terminal is reset to the original mode thereafter. Inaddition the mode change information may contain a minimum timeindication on how long the mode change should apply.

Advantageously, the transmitting and receiving means of the mobileterminal receives the system information messages of the broadcastchannel, whereby the system information messages comprise indicatinginformation indicating a channel in which the mode change information istransmitted, said channel being different from the broadcast controlchannel, and receives said mode change information on the differentchannel.

Advantageously, the control means, upon detecting mode changeinformation, switches off at least the transmitting part of a highfrequency portion of the mobile terminal. The mobile terminal couldstill receive reset messages, which reset the change mode, through itsreceiver. However, the receiver still would emit high frequency signalswhich could disturb other equipment. In case that there is norequirement for reset messages the whole high frequency part of themobile terminal could be switched off. Further, the entire mobileterminal could be switched off. Alternatively, the control meansdetecting mode change information switches the mobile terminal into asilent mode, e. g. a ringer off or a vibrating device on mode. As statedabove, the silent mode is a mode in which audible or acoustic signalsoutput from the mobile terminal are at least reduced in volume so thatdisturbance within the predetermined area is avoided. In case that theaudible or acoustic signals are suppressed completely, they are replacedby visual signals, vibration signals or the like.

Advantageously, when the mobile terminal is located in a cell adjacentto the predetermined area, the transmitting and receiving means receivesinformation on the position of the broadcast control channel of the basestation according to the present invention for protecting thepredetermined area, then, the control means of the mobile terminaldetermines the receiving power of the broadcast control channel of thebase station. During a conversation the mobile terminal will report backthese measurements, from which the system will realise that the mobileterminal is approaching the predetermined area and will then be able toissue a warning information, either through audible sounds, e. g. theearpiece or the ringer, or by signalling information to the mobileterminal, which will then behave according to pre-set behaviour. Thismeans, that if the mobile terminal is in a normal telecommunication celladjacent or surrounding the predetermined area, the system informationmessage received by the mobile terminal from the current normal basestation indicates the position of a broadcast control channel, on whichthe base station in the predetermined area for protecting thepredetermined area transmits the mode change information. In case thatthe receiving power of the system information message in the broadcastcontrol channel of the base station in the predetermined area is strongenough, which indicates that the mobile terminal is approaching orwithin the predetermined area, a alarm signal is output to warn the userthat the mode of his mobile terminal will be changed soon. This is veryhelpful during a phone call. If a user using a mobile terminal is in atelephone conversation and approaches the predetermined area, in whichthe operation mode of the mobile terminal will be changed, he receives awarn signal and is thus able to either terminate the conversation orstep further away from the predetermined area to be able to continue hisconversation.

In the following description, the present invention is explained in moredetail by means of preferred embodiments thereof relating to theenclosed drawings, in which

FIG. 1 shows a block diagram of a base station according to the presentinvention and;

FIG. 2 shows a block diagram of a reduced base station according to thepresent invention and;

FIG. 3 shows a block diagram of a mobile terminal according to thepresent invention and;

FIG. 4 shows a principle outline of standard cellsites adjacent to areasto be protected according to the present invention and;

FIG. 5 shows the principle system architecture of a cellular networkaccording to the present invention.

The base station 1 shown in FIG. 1 is a base station for protecting apredetermined area from disturbing usage of mobile terminals of awireless cellular telecommunication system. The base station 1 comprisesgenerating means 2 for generating mode change information for changingan operation mode of the mobile terminals within the predetermined areato protect the predetermined area. The base station 1 further comprisestransmitting means 3 for transmitting mode change information generatedin the generating means 2 within the predetermined area using systeminformation messages of a broadcast control channel of the wirelesstelecommunication system. The mode change information is transmittedfrom the transmitting means 3 by means of an antenna 5.

The base station 1 can be a normal base station for transmitting andreceiving signals in the wireless cellular telecommunication system or aspecial base station as outlined in FIG. 2 only transmitting said modechange information for protecting the predetermined area. In the firstcase, the base station 1 further comprises receiving means 4 as shown inFIG. 1. In the second case, the base station 1 essentially comprisesonly the generating means 2 and the transmitting means 3, so that a verysimple and cost-effective solution is achieved. In the second case, thebase station 1′ as shown in FIG. 2 comprises only a transmitting means3′ and a generating means 2′ and serves only for transmitting the modechange information within the predetermined area without having furthercapabilities. The transmitting means 3′ and the generating means 2′ havethe same functions as the transmitting means 3 and the generating means2, respectively. For ease of operation an external or internal controlterminal or PC 19 could be connected.

Of course, the base station 1 in FIG. 1 comprises further elements whichare necessary to operate the base station 1 in the respectivetelecommunication system, e. g. a control means 6 and so on. The basestation 1 operates and transmits the mode change information on thebasis of the wireless cellular telecommunication system, i. e. theGSM-system or the like. This has the advantage that mobile terminalsentering the predetermined area can be addressed on the basis of thewireless cellular telecommunication system to change an operation modethereof to protect a predetermined area without requiring a differentreceiving section for the mode change information transmitted from thebase station 1. This has the additional advantage that the mobileterminals, as e. g. the mobile terminal 7 shown in FIG. 3, can be commonmobile terminals for the wireless telecommunication system, which onlyneed to be adapted to receive and process the mode change information.Thus, the configuration of normal mobile terminals for the wirelesstelecommunication system does not need to be changed essentially.

In FIG. 3, a block diagram of a mobile terminal 7 according to thepresent invention is shown. The mobile terminal 7 comprises transmittingand receiving means 8 for transmitting information to and receivinginformation from base stations of the telecommunication system. Thetransmitting and receiving means 8 further receive mode changeinformation transmitted from a base station by means of systeminformation messages of a broadcast control channel of the wirelesstelecommunication system for protecting a predetermined area fromdisturbing usage of the mobile terminal. E. g., the base stationtransmitting the mode change information can be the base station 1 ofFIG. 1 or the reduced base station 1′ of FIG. 2. The transmitting andreceiving means 8 comprises a transmitting unit 9 and a receiving unit10. The receiving unit 10 of the transmitting and receiving means 8receives signals by means of an antenna 18. The received signals arethen processed in the mobile terminal 7 under control of a control means11. E. g., the received signals are decoded in a decoding means 15,whereby further processing steps depending on the structure of thesignals might be taken. At the end of the processing, the signals aretransformed into audible signals and output from a loudspeaker 13 incase they are voice signals, or answered by the mobile terminal in casethey are signalling information, or passed on to the data part or a datadevice in case they are data signals.

The mobile terminal 7 further comprises a microphone 12 for receivingand detecting acoustic signals. The signals input in the microphone 12are further processed under the control of the control means 11, e. g.coded in a coding means 14 and so on depending on the structure of thesignals in the telecommunication system, and then transmitted by thetransmitting unit 9 through the antenna 18. The mobile terminal 7comprises further elements for processing received signals and signalsto be transmitted besides the decoding means 15 and the coding means 14as shown in FIG. 3. The additional elements depend on the structure ofthe signals in the wireless telecommunication system, so that a largevariety of further processing units can be implemented.

The mobile terminal 7 further comprises a generating means 16 connectedbetween the control means 11 and the transmitting unit 9 and a timingmeans 17 connected with the control means 11.

FIG. 4 shows the topography of e. g. an airport terminal, where areas Aand B are the coverage areas of a cell site, covering the waiting loungeX. Areas C1, C2 and C3 indicate the coverage area of cell sites coveringpredetermined areas, e. g. the gangways towards an airplane, Y, Z1 andZ2. As long as a user is making phone calls or is walking in areas “A”and “B” his phone will work normally and nothing will happen. Once he isapproaching the area “C1” the network may issue warning indications tothe phone while it is in communication, warning the user that he iscoming closer to a predetermined area. Once the user enters the area“C1”, “C2” or “C3” the telephone will receive the mode changeinformation and change its mode accordingly. This functionality notnecessarily requires separate cell sites, this could also be handled inarea “C1” alone.

The base station 1 being located in an area which has to be protectedfrom a disturbing usage of mobile terminals regularly broadcasts modechange information which is received by mobile terminals, as e. g. amobile terminal 7, entering the predetermined area to change anoperation mode thereof so that the area is protected. Thereby, the modechange information is broadcasted from the base station 1 on the basisof system information messages in a broadcast control channel of thewireless telecommunication system.

FIG. 5 shows the basic structure of a cellular system, which comprisesat least two base stations 1, covering the areas A and B, a base stationcontroller 20, a switch 21 with a gateway to a public telephone network22, a register 23 which keeps information on the terminals of thiscellular network and possibly of visiting mobile terminals and themobile terminals 7 themselves. The base stations are connected with thebase station controller via a communication and signalling link, thebase station controller and the switch is connected via a communicationand signalling link, the register and the switch are connected by acommunication and signalling link, as well as the switch and the publictelephone network. The mobile terminals 7 and the base stations 1communicate by means of radio transmission.

Usually, when a mobile terminal is switched on the first time, it readsthe system information from the broadcast control channel. Once it hasthe knowledge about timing, channel structure, location including thenetwork identification of the particular base station of the respectivecell of the telecommunication system, the mobile terminal will try toregister itself with the network through this base station. This means,that the mobile terminal makes itself known to the network, so that thenetwork will be able to page the mobile terminal later on. After asuccessful registration a mobile terminal will listen regularly to thepaging channel of the respective base station in order to be able toreact on incoming phone calls. Furtheron, the mobile terminal monitorsbase stations in neighbouring cells, the channels of which are listed inthe system information of the current cell. A paging area can compriseseveral cells, in which a particular mobile terminal is paged. When amobile terminal is moving around in the network, the signal of the basestation of the current cell will become weaker and a signal from aneighbouring cell will become stronger. Eventually, the mobile terminalswitches to the base station of the neighbouring cell. This is true,when the mobile terminal is in the idle mode, when the mobile terminalis in the talk mode, a cell change, i. e. a hand-over, is initiated bythe network. In other cellular systems, e. g. CDMA One, the mobilestation itself would decide on its own whether to perform a handover ornot. Once the mobile terminal has switched to the base station of theneighbouring cell, it will again read all necessary information from thesystem information message broadcast on the broadcast control channelfrom the base station of the new cell. If this new cell belongs to thesame paging area as the previous cell, the mobile terminal will notperform a registration (location update). In case that the base terminalbelongs to a new paging area, the mobile terminal will perform aregistration (location update).

Thus, two scenarios are possible. The first scenario is that the mobileterminal 7 located within a predetermined area to be protected isswitched on being within the predetermined area. The mobile terminalwill then read the system information message in the broadcast controlchannel transmitted from the respective base station, e. g. the basestation 1 for protecting the predetermined area. Since the base station1 transmits mode change information by means of the system informationmessage, the mobile terminal 7 receives the mode change informationeither within or as a part of the system information message or throughanother channel indicated by the system information message and thenchanges its mode so that the area is protected.

The mode change information generated in the generating means 2 of thebase station 1 can be additional information to the system informationmessages or can replace at least partially the system informationmessages in the broadcast control channel. The mode change informationare thus comprised in the system information message, which is receivedby the base terminal 7 so that an operation mode thereof is changed toprotect the predetermined area.

Another possibility is that the system information messages generatedand transmitted from the base station 1 comprise indicating informationindicating a channel in which the mode change information istransmitted, whereby this channel is different from the broadcastcontrol channel. In other words, the system information messagetransmitted by the base station 1 in the broadcast control channel referto another channel, in which the mode change information is transmitted.The mobile terminal 7 receiving the system information message willreceive the indicating information and look on the other indicatedchannel, in which the mode change information is transmitted. Thus, themobile terminal 7 reads the mode change information by means of thereceived system information message. As stated above, a simple andcost-effective version of the base station 1 essentially comprises thegenerating means 2 and the transmitting means 3 so that only mode changeinformation is generated and transmitted by the base station 1. In thiscase, the system information messages contain the mode changeinformation and the standard or default system information messages inthe broadcast control channel. The mobile terminal 7 will then receivethe mode change information and change its mode correspondingly, withoutattempting a registration, e. g. location update. The mode changeinformation can also contain the reason for the mode change. In a moredeveloped version of the base station 1 the mode change informationreplace only a part of the system information message in the broadcastcontrol channel, so that further information like the reason for themode change, the level of the mode change or the like can be transmittedto the mobile terminal 7. Particularly, the mobile terminal 7 does notneed to register with the base station 1 for protecting thepredetermined area. It is sufficient, when the mobile terminal 7receives the mode change information from the base station 1 to changeits mode to protect the area. The base station of the predetermined areato be protected is thereby treated as a normal neighbouring base stationof an adjacent cell. In case that the mobile terminal 7 is registered toa normal base station in a cell of the telecommunication system, thisnormal base station comprises in its system information messagesinformation about the channels of the neighbouring base stations. If oneof the neighbouring base stations is the base station 1 for protectingthe predetermined area, the mobile terminal 7 will regularly monitor thesignal power of the base station 1 as it does with the other adjacentbase stations. The mobile terminal 7 can thereby monitor the broadcastcontrol channel of the base station 1 for protecting the predeterminedarea so that as soon as the receiving power exceeds a predeterminedthreshold the control means 11 of the mobile terminal 7 decides tochange a mode thereof since the predetermined area is reached.

In any case, the control means 11 of the mobile terminal 7 can cause theloudspeaker 13 to output an alarm signal to warn a user that he isapproaching or within the predetermined area to be protected and thatthe operation mode of the mobile terminal 7 will be changed soon toprotect the area. Thus, the user can decide to get away from thepredetermined area or, in case that a call is in progress, he canterminate the conversation quickly.

Upon receiving a mode change information by the transmitting andreceiving means 8, the control means 11 of the mobile terminal 7 detectsthe mode change information and changes the mode of the mobile terminal7 depending on the received mode change information so that thepredetermined area is protected. The control means 11 can therebymaintain the changed mode as long as mode change information isregularly received and detected. As soon as mode change information isno longer received, the mobile terminal 7 is reset to its original modebefore the mode change. The timing means 17 of the mobile terminal 7 maycalculate the time period since the last reception and detection of themode change information and for comparing the time period with apredetermined time threshold, whereby the mobile terminal 7 is reset tothe original mode in case that the time period exceeds the timethreshold. If a time indication is present in the mode changeinformation, the MS must not attempt a reset before the indicated time.

Alternatively, the control means 11 maintains the changed mode until thetime period received as time information together with the mode changeinformation has expired, whereby the mobile terminal 7 is reset to theoriginal mode thereafter. In this case, the generating means 2 of thebase station 1 needs to generate additional time information to the modechange information to indicate how long the changed mode in the mobileterminal 7 should be maintained. Another possibility is to store thetime information in the mobile terminal 7 so that the time period duringwhich the changed mode has to be maintained is provided by the mobileterminal 7 itself.

If e. g. the predetermined area to be protected is a hospital, where ithas to be assured that mobile terminals are not used, the mobileterminals advantageously maintain their changed mode as long as the modechange information is received. In this case, one or more base stations1 are located in the hospital and regularly broadcast the mode changeinformation. In other areas, e. g. hospitals, it might be only importantto change the mode of mobile terminals during a short period of time.Thus, a base station 1 could be located at the entrance, so that theoperation mode of mobile terminals entering the hospital are changed.The changed mode only needs to be maintained during the visit. Thus, apredetermined time period, e. g. 30 minutes, 60 minutes or the like, issufficient and the mobile terminals could be reset to their originalmodes after expiration of this predetermined time period. A furtherpossibility might be to change the mode of mobile terminals uponreceiving a mode change information, e. g. at a boarding gate of anairport, to maintain the changed mode during the flight and to reset themode of the mobile terminals upon receiving a second mode changeinformation at the exit gate of the airport on the arrival.

Depending on the received mode change information, the control means 11of the mobile terminal 7 changes the operation mode thereof. If areaslike a hospital or airplanes are to be protected, the control means 11switches off at least a high frequency portion of the mobile terminal 7.The high frequency portion of the mobile terminal is the part causinginterference with other electronic or electric devices and thus theoperation of the high frequency part should be suppressed. In case ofthe mobile terminal 7 shown in FIG. 3, the control means 11 could switchoff at least the transmitting unit 9 of the transmitting and receivingmeans 8 upon receiving a mode change information. The mobile terminal 7is then still able to receive signals by means of the receiving unit 10,e. g. to receive information to reset the mobile terminal 7 to itsoriginal mode. Alternatively, the control means 11 could switch off theentire transmitting and receiving means 8 so that neither thetransmission nor the reception of signals is possible any longer. Inboth cases, however, the base band functions could still be available,so that a user still can edit information, input information to theinternal telephone book, store messages to be transmitted later on andthe like.

In other areas, e. g. restaurants, operas, theatres or the like, it issufficient to change the mode of the mobile terminal 7 into a silentmode, in which other people in the same area are not annoyed by audibleor acoustic signals output from the mobile terminal 7. Thereby it mightbe sufficient if the control means 11 simply reduces the volume of theacoustic signals to be output by the loudspeaker 13. Further, the volumeof signals to be output by the loudspeaker 13 could be completelysuppressed. Additionally to the reduced volume signals or replacing thesuppressed audible signals, the control means 11 might cause the outputof the visual signals on a display of the mobile terminal 7, theactivating of a vibration device of the mobile terminal 7 or the like toindicate incoming phone calls to a user.

What is claimed is:
 1. A base station for protecting a predeterminedarea from disturbing usage of mobile terminals of a wirelesscommunications system, comprising: a generator for generating modechange information for changing an operation mode of said mobileterminals to prevent said mobile terminals from operating in adisturbing mode, and for generating identifying information representingat least one group of mobile terminals that receive said mode changeinformation but are excluded from changing their operation mode; and atransmitter coupled to said generator for transmitting said generatedmode change information and said identifying information within saidpredetermined area by means of system information messages on abroadcast control channel of said wireless communication system.
 2. Thebase station of claim 1, wherein said mode change information replacesat least a portion of said system information messages on said broadcastcontrol channel.
 3. The base station of claim 1, wherein said modechange information is transmitted in addition to said system informationmessages on said broadcast control channel.
 4. The base station of claim1, wherein said system information messages include an identificationchannel on which mode change information is transmitted, saidlast-mentioned channel being different than said broadcast controlchannel.
 5. The base station of claim 1, wherein said transmitterregularly transmits said mode change information.
 6. The base station ofclaim 1, wherein said mode change information is operable to deactivateat least a high frequency portion of the mobile terminal that receivessaid mode change information.
 7. The base station of claim 1, whereinsaid mode change information is operable to turn off audible signalgenerators of the mobile terminal that receives said mode changeinformation.
 8. The base station of claim 1, wherein said mode changeinformation includes timing information to establish a time durationduring which the operating mode of the mobile terminal that receivessaid mode change information remains changed.
 9. The base station ofclaim 1, wherein said mode change information includes informationrepresenting the reason for the change in the operating mode of themobile terminal that receives said mode change information.
 10. Methodfor protecting a predetermined area from disturbing usage of mobileterminals of a wireless cellular communication system, comprising thesteps of: generating mode change information for changing an operationmode of said mobile terminals to prevent said mobile terminals fromoperating in a disturbing mode, and for generating identifyinginformation representing at least one group of mobile terminals thatreceive said mode change information but are excluded from changingtheir operation mode; and transmitting said generated mode changeinformation and said identifying information within said predeterminedarea by means of system information messages on a broadcast controlchannel of said wireless communication system.
 11. The method accordingto claim 10, wherein said mode change information replaces at least aportion of said system information messages on said broadcast controlchannel.
 12. The method according to claim 10, wherein said mode changeinformation is transmitted in addition to said system informationmessages on said broadcast control channel.
 13. The method according toclaim 10, wherein said system information messages include anidentification channel on which mode change information is transmitted,said last-mentioned channel being different than said broadcast controlchannel.
 14. The method according to claim 10, wherein said mode changeinformation is regularly transmitted.
 15. The method according to claim10, wherein said mode change information is operable to deactivate atleast a high frequency portion of a mobile terminal that receives saidmode change information.
 16. The method according to claim 10, whereinsaid mode change information is operable to turn off audible signalgenerators of the mobile terminal that receives.
 17. A mobile terminalfor a wireless cellular telecommunication system, comprising:transmitting and receiving means for transmitting information to andreceiving information from base stations of said telecommunicationsystem and for receiving mode change information transmitted from a basestation by means of system information messages on a broadcast controlchannel of said wireless telecommunication system for protecting apredetermined area from disturbing usage of the mobile terminal; andcontrol means for detecting received mode change information and a modeof the mobile terminal depending on the received change information sothat said predetermined area is protected, wherein in a case of beinglocated in a cell adjacent to said predetermined area said transmittingand receiving means receives information on the position of saidbroadcast control channel of the base station for protecting saidpredetermined area, said control means determines the receiving power ofsaid broadcast control channel of the base station and outputs an alarmsignal to a user either through audible sounds or signaling means that amode of the mobile terminal will soon be changed.
 18. The mobileterminal according to claim 17, wherein said control means maintainssaid changed mode as long as the mode change information is received anddetected.
 19. The mobile terminal according to claim 17, including atiming means for calculating the time period since the last receptionand detection of said mode change information and for comparing saidtime period with a predetermined time threshold, whereby the mobileterminal is reset to an original mode in the event that the time periodexceeds said time threshold.
 20. The mobile terminal according to claim17, wherein said control means maintains said changed mode until a timeperiod represented as time information included with said mode changeinformation has expired, whereby the mobile terminal is reset to anoriginal mode thereafter.
 21. The mobile terminal according to claim 17,including switching means which switches said broadcast control channelnormally received by said mobile terminal to a mode change informationchannel.
 22. The mobile terminal according to claim 17, wherein saidcontrol means detecting said mode change information deactivates atleast a high frequency portion of the mobile terminal.
 23. The mobileterminal according to claim 17, wherein said control means detectingsaid mode change information turns off audible signal generators of themobile terminal.